Field of the Invention
The present invention relates to a GPS receiving apparatus and a computer readable storage medium.
Description of the Related Art
Lately, techniques to measure a position using a GPS (Global Positioning System) have been developed. The GPS receiving apparatus receives a signal transmitted from a plurality of GPS satellites and obtains GPS information regarding the GPS satellite from the received signal. Then, the GPS receiving apparatus calculates the distance to each GPS satellite based on the GPS information to measure the position of the apparatus. The GPS receiving apparatus is included in a vehicle navigation system, portable phone, camera and the like.
If the GPS receiving apparatus is being used for the first time or has not been used for a long period of time, when the power of the apparatus is turned on, all of the GPS satellites are set as targets to make an attempt to sequentially receive signals from the satellites. A signal from the GPS satellite used in measuring the position is received and the position is measured (cold start). When the power is turned on after the GPS receiving apparatus has executed a reception operation, the GPS receiving apparatus uses the satellite position from the previous measured position (last GPS information) to perform GPS reception operation (hot start, warm start).
For example, a GPS receiving apparatus has been proposed that is started with the hot start mode when the information regarding the GPS satellite is stored in the backup memory, and that is started with the cold start mode when the information regarding the GPS satellite is not stored in the backup memory (see, for example, Japanese Patent Application Laid-Open Publication No. 2003-344523).
However, when the above-described GPS receiving apparatus measures a position that is far from a position which was previously measured, the layout (relative position) of the satellites with respect to the GPS receiving apparatus is greatly different than at the previous measured position. Therefore, even if an attempt is made to start the apparatus with the hot start mode or the warm start mode, there are cases where the calculation used to measure the position does not end. In this case, the apparatus is restarted with the cold start mode after a predetermined time limit passes. Therefore, there is a problem with the above-described GPS receiving apparatus whereby when the apparatus has moved a distance equal to or more than a predetermined distance from the previous measured position and an attempt is made to start the apparatus with the hot start mode or the warm start mode, the measuring time becomes longer than if the apparatus were started with the cold start mode from the beginning.